Correlation of β-catenin expression in non-small cell lung cancer to prognosis and CD8 positive cells infiltration.

142 Background: It was reported that β-catenin expression in tumor cells suppresses dendritic cell infiltration into tumor in mouse model of melanoma. It results in less of tumor infiltrating lymphocytes. In non-small cell lung cancer (NSCLC), it is not well understood that β-catenin is involved in cancer immunity in that context. Methods: We studied the association between β-catenin expression and CD8 positive cells infiltration in NSCLC. Ninety-one patients with NSCLC who had complete surgical resection during January 2013 to June 2015 were subjected. β-catenin expression of tumor cells and CD8 positive cells infiltration were analyzed by immunohistochemistry. Survival analysis including over-all survival (OS) and progression-free survival (PFS) were also statistically examined by log-rank test. Results: Fourteen cases (15%) were β-catenin positive. Among 14 β-catenin positive cases, only 2 cases (14%) had CD8 positive cells infiltration. Seventy-five cases (97%) had CD8 positive cells infiltration in β-catenin negative tumors (p < 0.01). Squamous cell carcinoma was relatively higher level of expression than others (44% vs. 9%) and mean primary tumor size was larger in β-catenin positive tumors (3.6 cm) than those in negative tumors (2.7 cm). Median OS was 43.8 months and median PFS was 37.0 months in β-catenin positive group. They were not reached in β-catenin negative group. Both OS and PFS were shorter in β-catenin positive cases (p < 0.01). Conclusions: In NSCLC, β-catenin expression was negatively associated with CD8 positive cells infiltration and poor prognosis. We furthermore will focus on the association between β-catenin expression in tumor and clinical efficacy or resistant mechanism of immune checkpoint blockades.